The invention relates to a method for the preparation of molding compositions and to the molding compositions themselves, which are composed of epoxy resins with substituted ureas or polyureas as hardeners.
The subject matter of German "Offenlegungsschrift" 1,770,814 is thermoplastically workable, thermosetting combinations of epoxy resin and hardener having a long shelf life, which can be prepared by mixing polyureas containing two and preferably three and more urea groups in the molecule, with epoxy resins. The polyureas have the structural framework --[NH-CO-NH-R]--.sub.n.sub.+1, n in the formula being equal to or greater than 1 and R being the bivalent radical of a diamine or of a polyamide of low molecular weight. R can also have a valence greater than 2 provided that the amount added does not permit any cross-linking. These resin-hardener combinations have the advantage that they do not react at normal temperature and are thus stable in storage. They have thermoplastic properties over a wide temperature range and can be worked in the manner of thermoplastics, for example in extruders and injection molding machines. Not until the temperature rises, usually above 150.degree. C, do the thermosetting characteristics prevail.